1. Field of the Invention
The invention relates to a fuel injecting device for an engine.
2. Description of the Related Art
In the engine field, it is known that an injection of fuel into a cylinder of the engine (hereinafter referred to as "pilot injection") is operated to decrease an amount of the NO.sub.X and noises generated in the engine before an injection of fuel into a cylinder is operated to drive the engine. When the fuel is injected into the cylinder by the pilot injection, the fuel is burned in the cylinder to increase a temperature in the cylinder.
Further, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 8-261052, it is known that an injection of fuel into a cylinder of the engine (hereinafter referred to as "post injection") is operated to feed the fuel as reducing agent to a catalyst for purifying an exhaust gas after an injection of the fuel into the cylinder is operated to drive the engine. The catalyst purifies the NOx included in the exhaust gas with the reducing agent. When the fuel is injected into the cylinder by the post injection, the fuel evaporates in the cylinder and is discharged from the cylinder as the evaporated fuel.
However, if a temperature in the cylinder is lower than a predetermined temperature when a predetermined amount of the fuel is injected into the cylinder by the pilot or post injection, a certain amount of the fuel may adhere to an inner wall of the cylinder. The fuel adhering to the inner wall of the cylinder may pass through the clearance formed between the inner wall of the cylinder and a piston inserted into the cylinder. Therefore, the temperature in the cylinder cannot be increased to an intended temperature in connection with the pilot injection. Also, an intended amount of the fuel cannot be fed to the catalyst to purify the exhaust gas.
Further, in the case that an engine oil for lubricating parts of the engine is provided under a piston inserted in the cylinder, when the fuel adhering to the inner wall of the cylinder may pass through the clearance formed between the inner wall of the cylinder and the piston, the engine oil is deteriorated.
Therefore, the object of the invention is to provide a fuel injecting device for an engine which can inject the fuel into the cylinder without the adhering of the fuel to the inner wall of the cylinder.